Jürgen Klinsmann, the USA coach, has said he is optimistic forward Jozy Altidore can recover from an injured left hamstring in time to return to the World Cup.

Altidore underwent an MRI exam on Tuesday after the US squad returned to its Sao Paulo headquarters from Monday night's 2-1 victory against Ghana. Results were not immediately available, leaving Altidore's World Cup in doubt because hamstrings are not always quick to heal.

The 24-year-old, who plays for Sunderland in the Premier League, suffered the injury after 22 minutes of the first half leading up to the dramatic victory over Ghana. He had been running down a ball with Ghana's John Boye when he grabbed the back of his left leg and fell to the ground in pain. He was replaced by Aron Johannsson.

"With Jozy we've got to see how he now reacts the next couple days with his hamstring and we're full of hope that he comes back still in this tournament – and that's what we kind of work on every day," Klinsmann said. "The medical staff is doing a tremendous job [for] weeks so we still have to hope that Jozy will be back. How quickly? That is down to his healing process."

"Obviously we all hope he'll be all right," midfielder Alejandro Bedoya said. "I'm sure if he's able to work hard we're going to get him back. We have players that can play different roles and come in and do a job. Last night we had two subs come in and add something to the game. Aron is a good player and I think he did well last night under the circumstances. It was hard to get him the ball."

After the game Altidore told reporters: “I was sprinting and I felt something … I was crushed. I knew right away I couldn’t continue. It was the worst feeling.”

Altidore was replaced by Aron Johannsson, not a like-for-like replacement in terms of physical presence and the ability to hold up ball for others. Jürgen Klinsmann, the USA coach, said: “It was not easy to swallow the first pill of Jozy coming off the field. He is very, very important for us.”

In 2012-13, he scored 23 goals for AZ Alkmaar in the Dutch Eredivisie. He has also played for the New York Red Bulls, Villarreal, Hull City and the Turkish club Bursaspor.

The other strikers in the USA World Cup squad are Seattle's Clint Dempsey, who scored after 31 seconds against Ghana before having his nose broken by a kick in the face – Klinsmann said “I broke mine three or four times and it’s all right; we’ll give him a few days” – and Chris Wondolowski of the San Jose Earthquakes.

Klinsmann caused controversy before the World Cup when he left Landon Donovan out of his 23-man squad. The Los Angeles Galaxy forward has 156 international caps and a record 57 goals. Terrence Boyd of Rapid Vienna was the other striker from Klinsmann's provisional 30-man selection not to make the final cut.

On Monday night, Dempsey, the USA captain, said of Altidore: “My heart goes out to him because he's been working hard. He's been looking sharp. You know how much he wanted to do well … You could see the tears in his eyes going back to the locker room.

“We wish him a speedy recovery. He's a big player for us. It hurts to have him go out of the game … but other players have to step up now."

The central defender Matt Besler was also replaced due to a hamstring injury, at halftime and by the scorer of the winning goal, John Brooks. The team said Besler's withdrawal was precautionary, due to hamstring tightness.

The USA's next match in Group G is against Portugal – who were beaten 4-0 by Germany on Monday – in the Amazon city of Manaus on Sunday. Kick-off is at 6pm ET.